Method for logging wells



May 10 1955 s. E. BucKLEY ETAL 2,708,155

METHOD Foa LOGGING WELLS Filed April 30, 1952 3 Sheets-Sheet 2 May l0 1955 s. E. BucKLEY Erm.

METHOD FOR LOGGING WELLS 5 Sheets-Sheet 3 Filed April so. 1952 'l TCH BOX (303 k.alo

sox 507 7-FILTER CAKE Fl G. -5.

INVENTm Whitman D. Mounce, By Stuart E. Buckley,

ELECTRICAL C BLE Mnrnon Fon Leconte WELLS Stuart E. Buckley and Whitman D. Monnce, Houston,

Tex., assignors, by mesne assignments, to Esso Research and Engineering Company, a-corporation of Delaware Application April 30, 1952, Serial No. 285,223

18 Claims. (Cl. 23-230) The present invention is directed to a method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore. More particularly, the invention is directed to prospecting a well bore penetrating an earth formation containing hydrocarbons and other carbonaceous matter.

The present invention may be briey described as involving the introduction into a well bore penetrating an earth formation of an oxidizing agent reactable with hydrocarbons or other carbonaceous matter in said formation and contacting the oxidizingr agent with the'formation containing the hydrocarbons or other carbonaceous matter. The reaction between the oxidizing agent and the petroliferous substance or hydrocarbon in the formation causes the generation of heat and/ or the generation of an elastic wave, such as a sound wave, or a pressure impulse. The formation of heat or the generation of an elastic wave may be detected by thermometric methods or accoustical methods or by pressure indicating devicesat the earths surface which allows the presence of hydrocarbons to be indicated directly. Since the oxidizing reaction between the oxidizing agent and the hydrocarbon or petroliferous substances in the formation being tested may form oxidation products such as carbon dioxide, carbon monoxide and acids, the presence of such hydrocarbons may also be indicated chemically. In short, when carbon monoxide and carbon dioxide are formed, the presence of such gases may be determined chemically by means well known to the chemist and the presence of hydrocarbons in the formation thus be determined. Likewise, the oxidation of hydrocarbons or petroliferous substances in or adjacent the formation by the oxidizing agent may cause the formation of acids which likewise may be determined chemically by titration or may be indicated by potentiometric methods. In any event it is contemplated in the practice of our invention that the reaction will cause one or more effects which may be detected and displayed whereby the presence of hydrocarbons -in the formation is indicated.

In the practice of our invention it is possible to employ I as oxidizing agents, oxidizing agents from a large number of materials which are known to react with hydrocarbons. Among these known oxidizing agents reactable with hydrocarbons are chlorine, perchloric acid, liquid oxygen, air, hydrogen peroxide, chlorosulfonic acid, fluorosulfonic acid and the like. It is also possible to use the other perhalogen acids, such as pertluoric acid, periodic acid and perbromic acid. Other oxidizing agents which may be suitable in the practice of the present invention are a mixture of nitrogen dioxide and aniline, potassium permanganate, chlorine, aqua regia, and the like. When chlorine is employed, it will be necessary to employ a catalyst therefor. For example, red phosphorus in a nely divided condition may be dispersed in the liquefied chlorine. Likewise when the perhalogen acids are employed, it will be desirable to use a catalyst to cause the oxidation reaction to proceed spontaneously at a temperature such as that encountered in a well bore.

2,708,155 Patented May 10, 1955 In.' For example, it is possible to employ perchloric acid having a strength in the range from 70% to 84% HClO4 and temperatures down to as low as 40 C. by using a catalyst such as ceric ammonium nitrate. Other catalysts may be employed such as, for example, ammonium vanadate and osmium tetraoxide.

The temperature to be employed in the practice of the present invention wherein a petroliferous substance in a formation is caused to react with an oxidizing agent may range from substantially less than 30 C. up to about 500 C. Pressures may range from the pressure normally found in a well bore, where hydrocarbons are encountered, up to pressures as high as 20,000 pounds per square inch.

The invention may be practiced by introducing an oxidizing agent into contact with an earth formation penetrated by a well bore. This may be done suitably by disturbing or disrupting thefilter cake which ordinarily sheaths the permeable sections of the well bore. By disrupting the lilter cake the formation is exposed which may or may not contain hydrocarbons. The oxidizing agent is then introduced directly into contact with the exposed face of the formation and the reaction caused to proceed. The oxidizing agent selected will determine whether or not it will be necessary to apply heat at the point where the oxidizing agent is contacted with the formation. By employing perchloric acid of a suitable strength of HC1O4. reaction may be obtained at temperatures as low as 40 C. At a temperature of C. the reaction proceeds with moderate speed and at a temperature of C. the reaction between perchloric acid and hydrocarbons is violent. Actually lower temperatures than 40 C. may be encountered in an earth formation and We do not intend to limit ourselvesV by such temperatures as recited. The temperature of the earth formation may be substantially less than 30 C. Thus, the temperature necessary to initiate the reaction may be reduced by employment of suitable catalysts. For example, by use of ceric ammonium nitrate dissolved in water and added to the perchloric acid it is possible to obtain an explosive reaction at temperatures as low as 40 C.

The invention will be further illustrated by reference to the drawing in which:

Fig. l is an illustration of an embodiment in partial section suitable for practice of our invention;

Fig. 2 is an enlarged View in partial section of a detail of Fig. l;

Fig. 3 is a modification of the device of Figs. 1 and 2;

Fig. 4 is an illustration of apparatus allowing continuous logging of a well bore in accordance with our invention;

Fig. 5 presents a View of a modification of Fig 4; and

Fig. 6 illustrates a view of apparatus for conducting the invention.

In the several figures of the drawing, identical numerals will be employed to designate identical parts.

Referring now to Figs. 1 and 2, numeral 11 designates a well bore in an earth formation 12 which is lined with a lter cake 13 resulting from drilling operations employing a conventional type of drilling mud. Arranged in the well bore 11 is a body member 14 which is suspended from a wellhead, not shown, by a cable 14a which may be, and in this particular instance is, an electrical conductor cable. The body member 14 may be positioned adjacent a wall of the well bore as is shown `der 15 which may be formed integrally with the body member 14 but preferably is bored in a block member 16. Arranged within the piston cylinder 15 is a piston 17 which is provided on a free end thereof with a deformable sealing member 1S, the function of which will be described in more detail hereinafter. It will be noted that the block 16 is provided with an enlarged portion 19 and that a cavity 20 is defined by the enlarged portion 19 to accommodate the deformable sealing member 18 as the piston member 17 moves in the piston cylinder 15.

The body member 14 has arranged within it an exhaust reservoir 21, a hydraulic fluid reservoir 22, a first piston cylinder 23 and a second piston cylinder 24. The body member 14 also has arranged within it a cavity 25 and a chamber 26 which is adapted to contain a fluid oxidizing agent.

Arranged in the body member 14 above the hydraulic fluid reservoir 22 and below the block member 16 is a piston cylinder 27 which allows the piston 17 to be moved by the effect of the drilling mud pressure on the hydraulic iiuid reservoir 22.

The piston cylinders 23 and 24 are connected to the hydraulic fiuid reservoir 22 through a conduit 28 and a manifold 29. Connected to manifold 29 by conduit 30a is a first solenoid valve 30 which has a conduit 31 connecting into a T-shaped connection means 32 which serve to connect the piston cylinder 24 by a connection means 33 with the conduit 31 and the manifold 29. The T-shaped member 32 has a conduit 34 connected thereto which in turn, is connected to a second T-shaped member 35 which allows hydraulic iluid to be transmitted to piston cylinder 23 by connection 36. The T- shaped member 35, in turn, is connected by a still further conduit 37 to a second solenoid valve 38 which connects by conduit 39 to manifold 40 which, in turn, connects by conduit 41 to exhaust reservoir 21.

Arranged within the piston cylinders 23 and 24, respectively, are pistons 42 and 43 provided with piston arms or rods 44 and 45 which, in turn, are connected pivotally at points 46 and 47 with spring members 48 and 49 which are in themselves pivotally connected at points 50 and 51 with body member 14 to allow the latter to be moved to the wall of the wellbore 11 as will be described further.

The manifold 29 has connected thereto by conduit 60a a third solenoid valve which is connected by conduit 61 to a passageway 62 and to piston cylinder 15 in the block 16. A conduit 63 connects into a passageway 64 in the block 16 and to piston cylinder 15 and to a fourth solenoid valve 65 which connects by conduit 66 into manifold 40.

A fifth solenoid valve is connected to manifold 29 by conduit 70a and connects by conduit 71 into the piston cylinder 27 as will be seen in the sectional view of Fig. 2. Piston cylinder 27 has arranged in it interconnected pistons 72 and 73 which are connected by a piston rod 74. It will be noted that piston 7 2 has an area substantially larger than the area of piston 73 and it will be further noted that the arrangement of conduit 71 allows the hydraulic fiuid to be exerted against piston 72.

The purpose of pistons 72 and 73 is to allow the drilling mud pressure to be used as a motivating force in actuating piston 17 as will be described. As will be seen, piston cylinder 27 is connected at its smaller end to a conduit 75 which, in turn, connects with a passageway 76 in the block 16 and communicates thereby with the piston cylinder 15. The piston cylinder 27 is also connected at its larger end with conduit 77 which, in turn, connects with a sixth solenoid valve 78 connecting by conduit 79 to manifold 40.

Referring specifically to Fig. 2, it will be noted that the piston 17 is provided with an inner piston 90 which has on a free end thereof a cutting member 91 which is adapted to cut the filter cake 13 sheathing the wellbore 11. The piston is arranged in an inner chamber h 92 of the piston 17 and communicates with the piston cylinder 15 through an opening 93 in the wall of the piston 17. The piston 17 is suitably sealed by sealing means 94 and 95 while the piston 90 is also provided with seals 96 and 97 for operation thereof.

The piston 17 has adjacent a free end thereof enclosed by the seal 18 a port 100 which communicates with the space 101 enclosed by the seal 18. The port or conduit is connected by a conduit 102 to a seventh solenoid valve 103. This solenoid valve is provided with a bellowstype arrangement 104 in which is positioned an iron rod 105. Spaced above the bellows arrangement is a magnet means 106 which on energization, as will be described, serves to draw the iron rod 105 upwardly and to lift the seating means 106a on the end of the iron rod 105 olf the seat 107 in the bellows arrangement 104. It will be noted that the bellows arrangement means 104 is connected by a conduit 108 to an eighth solenoid valve 109 which, in turn, is connected by conduit 110 to the reservoir 26 which carries the fluid oxidizing agent.

It will be noted that the cavity 25 is open to the well and that the reservoir 26 may be constructed of a deformable material to allow well pressure to be exerted directly thereon. It is to be further noted that the hydraulic fluid reservoir 22 may likewise be constructed of a deformable material and that the reservoir 22 is also exposed to the well pressure through ports 111 in the body member 14.

The solenoid valves 30, 60, and 70 are connected by electrical conducting means 120, 121 and 122 to electrical energy means not shown at the wellhead and which are carried thereto through electrical conductor 123 which, in turn, connects with the electrical conductor cable 14a. Similarly, the solenoid valves 38, 65 and 78 are also connected by electrical conducting means 124, 125 and 126 to electrical energizing means at the wellhead and carried thereto by electrical conductor 123 and electrical conductor cable 14a, Similarly, the solenoid valve 103 is connected by electrical connecting means 127 to electrical conductor 123 which, in turn, is carried to the earths surface and connected to electrical energizing means, not shown. In a similar manner, the magnetizing means 106 is also connected by electrical connecting means 128 to electrical conductor 123 which is then carried to the wellhead through electrical conductor cable 14a.

It will be noted that the piston 17 carries thermocouple adjacent a free end thereof. The purpose of this thermocouple is to measure a temperature increase caused by reaction of iiuid oxidizing agent with petroliferous or organic substances with which a fluid oxidizing agent may come into contact when it is released as will be described further. It will be noted that the thermocouple 140 is connected by electrical connecting means 141 to electrical conductor 123 and is carried to the earths surface through electrical conductor cable 14n. The electrical connection means 141 passes around the piston cylinder 17 in the space 20 and through the block 16 by way of opening 142.

Referring now to Fig. 3 which is a modification of the apparatus of Figs. 1 and 2 for use in our invention, it will be seen that in general a similar apparatus is obtained but that the apparatus of Figs. l and 2 has been modified to allow a continuous log of the well 11. it will be noted in Fig. 3 that the deformable bag member 26 of Figs. l and 2 has been replaced by a pressure cylinder 150 arranged in a cavity 151 of the body member 14. 'Ihis cylinder contains fluid oxidizing agent under pressure sufficient to force it into the formation as will be described. The block member 16 which is similar to the block member 16 of Figs. l and 2 is provided with a piston cylinder 152 in which is arranged a piston 153 carrying on a free end thereof a clevis arrangement 154 in which a rotatable knife member 155 is arranged. The rotatable knife member 155 defines a plurality of knife edges 156 which are designed to cut through the filter cake 13 and contact the formation 12 as the member 155 rotates. The member 155 is provided with a plurality of ports 157 through which oxidizing agent is injected as will be further described. The member 155 also is provided with a plurality of thermocouples 158 for registering a temperature increase in the formation 12. The piston 153 is provided with seals 159 and 160 to allow the piston to be moved to the right and to contact the lter cake 13 and formation 12. The pressure cylinder 150 is connected by a conduit 110 to a solenoid valve 109 which, in turn, is connected by a conduit 160 to a passageway 161 in the enlarged portion 19 of the block member 16. The passageway 161 connects by a conduit 162 with a shaft 163 on which the rotatable member 155 rotates. This is a hollow shaft and communicates with the ports 157 through passageways in the member 155 which connect to the shaft 163. The thermocouples 158 are severally connected to an electrical connection means 164 which, in turn, connects to electrical conducting means 123 and thence carried to the earths surface through electrical conducting cable 14a.

Referring now to Fig. 4, apparatus is provided for continuous well logging in accordance with our invention. In the apparatus of Fig. 4 a body member 200 is L suspended from the wellhead by an electrical conductor cable 14a. Arranged in the body member 200 is a pressure cylinder 201 which contains fluid oxidizing agent of the type illustrated. The body member 200 is provided with a plurality of pairs of spring biased arms 202, 203 and 204. The arms 202, 203 and 204 are arranged to be biased outwardly from the body member 200 by springs 205, 206 and 207. The spring biased arms 202 are provided with a cutting edge or knife 208 on an end thereof and below it a recess 209 in which is arranged a thermocouple 210. Likewise spring biased arm 203 is provided with a recess 211 in which is arranged a thermocouple 212. Spring biased arms 203 are provided with a second recess space 213 by way of which oxidizing agent is injected into the formation 12 as will be described. Like spring biased arm 202, spring biased arm 204 is provided with a recess 214 in which is arranged thermocouple 215. The thermocouples 210, 212 and 215 are connected by an electrical connecting means 216, 217, and 218 to electrical conductor means 219 which carry the electrical connection means to electrical conductor cable 14a and thence to the earths surface. The recess 213 communicates with a passageway 220 in arms 203 and thence by conduits 221 with a conduit 222 which connects into a solenoid valve 223 which is electrically connected by electrical connection means 224 to electrical conducting means 219. The solenoid valve, in turn, connects by conduit 225 with a passageway 226 in a block member 227 in body member 200 which communicates, in turn, by conduit 228 with the pressure cylinder 201 containing the oxidizing agent.

The apparatus of Fig. 5 illustrates a tripping and releasing means for releasing the spring biased arms 202, 203 and 204. This tripping and releasing means is not shown in Fig. 4 for reason of clarity and to one skilled in the art it is evident that several such releasing means may be employed. The spring biased arms are retained in a retracted position by a pin 250 connected to a solenoid mechanism 251 which is energized through electrical connection means 252. The spring biased arm such as 204 of Fig. 4 provided with a recess 214 has a projecting member 253 provided with an opening 254 through which the pin member 250 projects. As shown in Fig. 5 when the spring biased arms 204 are in the retracted position the pin 250 holds the same retracted inwardly against the body member 200.

The device of Fig. 6 illustrates the apparatus of Figs. l to 3 specifically in a borehole 11 penetrating an earth formation 12 in which it is desired to prospect in sections A, B, and C. The body member 14 is suspended from the wellhead 300 by electrical conductor cable 14a over a gin pole 301 carrying a sheave 302 over which the electrical conductor cable 14a is passed. A motivating means, such as a diesel engine 303, is provided to rotate drum 304 on which the electrical conductor cable 14a lll is reeled. Connected electrically by electrical connecting means 305 and 306 to electrical conductor cable 14a is a terminal box 307 which communicates by electrical leads 308 with a switch box 309. Electrical connecting means 310 are also provided to connect the electrical connection means communicating with the therrnocouples of the apparatus of Figs. 1 to 3 which transmits the electrical impulses to a chart mechanism 311 which may be a recording potentiometer which allows the temperature of the formations to be displayed thereon.

The apparatus of our invention works in the following manner with respect to Figs. l and 2. It may be assumed that the body member 14 is lowered in the well bore 11 to a point adjacent the formation 12 traversed by the well bore and it is desired to determine whether or not the formation 12 contains petroliferous or organic substances and the like. When the body member 14 has reached a desired point in the well bore traversing formation 12, the solenoid valve 30 is opened allowing the pressure exerted on the deformable bag reservoir 22 containing hydraulic oil to cause the hydraulic oil to flow into the piston cylinders 23 and 24. Since the areas of pistons 42 and 43 are greater than the cross sectional areas of the piston rods 44 and 45 which are exposed to well pressure, the hydraulic oil in bag 22 causes the pistons 42 and 43 to move, respectively, upwardly and downwardly, which causes spring members 48 and 49 to be compressed which positions the body member 14 against a wall of the well bore 11 as shown in Figs. l and 2. The solenoid valve 30 is closed after the body member 15 has been moved against the w'all of the well bore. Solenoid valve 70 is then opened by proper energization which causes hydraulic fluid to be exerted against the area of piston 72. The hydraulic fluid back of piston 73 is caused to ilow through conduit 75 into piston cylinder 15 exerting a force on the piston 17 and causing it to move to the right and providing a seal by the deformable member 18 with the filter cake 13. Thereafter the solenoid valve is energized which allows hydraulic fluid to move into the piston cylinder 15 through conduit 61 and pass through passageway 93 into the inner chamber 92 of piston member 17. This causes a force to be exerted against the piston 90 and moves it to the right and causes the cutting edge 91 to penetrate the lter cake 13.

After the filer cake has been cut by the cutting member 91, the solenoid valve 60 is closed and the solenoid valve is opened allowing the hydraulic oil in the inner chamber 92 to be released through conduit 63 into reservoir 21 through conduit 66, manifold 40 and conduit 41. As a result of the pressure being released into reservoir 21 the formation pressure is exerted against the piston which causes it to be moved to the left within the chamber 92. Thus the formation 12 is now exposed and any hydrocarbons or petroliferous substances and the like contained in the formation 12 may be contacted with the fluid oxidizing agent as will be described.

Aft-er the sequence of operations has been conducted as described, the solenoid valve 109 is opened and magnet means 106 is energized. As the magnet means is energized the iron rod is caused to move upward in the bellows arrangement 104 which lifts'the seating member 106:1 off the seat 107. Valve 109 is then closed and solenoid valve 103 is opened. Magnet means 106 is then de-energized allowing member 106a to seat on seat 107. Solenoid valve 103 is then closed. Since the drilling mud pressure exerted on bag 26 is greater than formation pressure the iiuid oxidizing medium is caused to ow, in the sequence described, through conduits 110, 108, and 102 into the area 101 enclosed by the sealing means 18 and thence into contact with formation 12 which has been exposed by the cutting edge 91. Thus, the oxidizing agent may be injected in controlled amounts. As a result of contact of the oxidizing agent with the formation 12, a reaction ensues between the oxidizing agent and any petroliferous or organic substances in the formation 12. This reaction liberates heat which results in a temperature increase in the area adjacent th-e thermocouple 140. This temperature increase is detected at the earths surface and is a direct indication of the presence of petroliferous or organic substances in the formation. Thereafter, when it is desired to move the device to a new location for testing the formation, the pressure exerted against pistons 42 and 43 is released by opening solenoid valve 38 and releasing pressure through manifold 40 and thence into exhaust reservoir 21. This frees the body member 14 and allows it to resume a normal position in the well. The piston member 17 may be retracted by opening solenoid valve 78 which releases hydraulic fiuid from the piston cylinder 27 releasing the piston 17 and allowing it to move to the left. When it is desired to test another formation or position in the well bore the sequence of operations may be repeated.

The apparatus of Fig. 3 functions in a similar manner to that of Fig. 1 and differs only in the way the filter cake is penetrated and the formation 12 is exposed for contact. The sequence of operations positioning the piston member 153 to the right for contact of the rotatable member 155 with the filter cake 13 and the formation 12 is generally similar to that described in Figs. l and 2. By virtue of the different areas of the pistons 72 and 73 in piston cylinder 27 the piston 153 is moved to the right and the rotatable member 155 contacts and penetrates the filter cake 13. As the body member 14 is moved upwardly in the well bore 11 the member 155 rotates, exposing the formation 12, since the filter cake 13 is penetrated and cut by the knife edges 156. Simultaneously with the exposure of the filter cake, the solenoid 109 is opened by energization thereof, releasing the oxidizing agent under pressure through conduit 110 and thence through conduit 160, passageway 161 and c onduit 162 and through pin 163 to the ports 157 and thence into contact with the formation 12. The passageway in pin 163 is so arranged that oxidizing agent flows only through a passageway communicating with a port 157 which is in contact with formation 12. If petroliferous or other organic substances are present in the formation 12 a reaction is effected which liberates heat and results in a temp-erature rise in the formation. This temperature rise is detected by thermocouples 158 and the impulses therefrom are carried to the earths surface for display on a chart like 311.

The apparatus of Figs. 4 and 5 operates similarly to the other apparatus employed to illustrate our invention. Referring to Figs. 4 and 5, a body member, such as body member 200, has been lowered into the well bore 11. After the body member 200 has been lowered a predetermined distance, the arms 202, 203 and 204 may be released by energizing solenoid 251 which retracts a pin 250, causing the arms to spring outwardly by virtue of their being spring biased. After arms 202, 203 and 204 spring outwardly they contact the filter cake 13. The arm 202 provided with a knife edge 208 pierces the filter cake 13 and causes the formation of a channel therein through which the other arms may follow. By opening solenoid 223 by suitable energization thereof, oxidizing agent under pressure is released through the passageways 220 into the recesses 213 and thence against the formation 12. Ternperature readings of the formation may be obtained by thermocouples 210, 212 and 215 before and after release of the oxidizing agent. Thermocouple 210 will allow the temperature of the formation to be determined before release of oxidizing agent. Thermocouples 212 will allow determination of the temperature right after release of oxidizing agent and thermocouples 215 will allow the determination of the temperature a short time after the formation has been contacted with oxidizing agent and a F reaction effected.

Fig. 6 illustrates the mode of using our invention with respect to the several other figures of the drawing in which a body member 14 is lowered into the well bore. After the body member 14 has been lowered a predetermined distance it may be raised by starting up engine 303 and reeling the electrical conductor 14a onto drum 304. If it is desired to prospect section C of formation 12 then the sequence of operations conducted with respect to Figs. l and 2 are practiced. Thereafter the body member 14 may be raised upwardly in the hole 11 and the sequence of operations repeated until the desired number of formations have been tested.

While our invention has been described with relation to specific apparatus for accomplishing the desirable ends thereof, it is to be clearly understood that we do not limit ourselves to this particular equipment, since other apparatus may be used. For example, it may be desirable to use a porous roller to contact the formation. It may also be desirable to provide a body of liquid oxidizing agent in the well at suitable intervals isolated from the well fluid by packers and causing the oxidizing agent to ow through the filter cake by application of pressure to force the oxidizing agent into the formation. The invention may also be practiced by pumping down the well bore a body or slug of oxidizing agent together with a fiuid for increasing the permeability of the filter cake. As the oxidizing agent comes into Contact with a formation containing petroliferous substances, these materials are oxidized by the oxidizing agent and heat is generated by the reaction. Thereafter, temperatures of the several formations may be determined and compared with the temperatures of the formations before they were subjected to heating caused by reaction of the oxidizing agent with the petroliferous substances, if any, contained therein.

It may also be desirable in the practice of our invention to inject a small quantity of oxidizing agent into the drilling fluid and circulate same in the well bore as drilling proceeds. As the drilling fluid comes into contact with a formation containing hydrocarbons or petroliferous substances a reaction is effected between the hydrocarbons contained therein and the oxidizing agent in the drilling fiuid which will cause a particular formation to exhibit a temperature greater than that normally encountered. A temperature log of the sotreated Well bore may then indicate the presence or absence of hydrocarbons in the formations traversed by the well bore. It is intended, therefore, that we are not to be limited to any specific apparatus given by way of illustration.

The nature and objects of the present invention having been completely described and illustrated, what we desire to claim as new and useful and to secure by Letters Patent is: Y

l. A method for prospecting in a well bore penetrating an earth formation containing carbonaceous matter and produced by a drilling method which deposits a filter cake lining on the well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, contacting at least a portion of the formation from which said filter cake has been so disrupted with an oxidizing agent reactable with carbonaceous matter in said formation, reacting said oxidizing agent and said carbonaceous mattei' to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said carbonaceous matter is indicated.

2. A method for prospecting in a well bore penetrating an earth formation containing carbonaceous matter and produced by a drilling method which deposits a filter cake lining on the well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, contacting at least a portion of the formation from which said filter cake has been so 9 disrupted with an oxidizing agent reactable with said carbonaceous matter in said formation, initiating and maintaining a reaction between said agent and carbonaceous matter to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal which is a measure of the content of carbonaceous matter in said formation.

3. A method for prospecting in a well bore penetrating an earth formation containing hydrocarbons and produced by a drilling method which deposits a filter cake lining on the well bore which comprises disrupting filter cake from a portion of the face of said formation in the bore hole, contacting at least a portion of the formation from which said filter cake has been so disrupted with an oxidizing agent reactable with the hydrocarbons in said formation, establishing a temperature zone adjacent said formation sufiicient to initiate and maintain a reaction between said oxidizing agent and hydrocarbons to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal which is a measure of the hydrocarbon content of said formation.

4. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing into said well bore an oxiding agent reactable with the petroliferous substance in the formation, contacting at least a portion of the formation from which said filter cake has been so disrupted with said oxidizing agent, reacting said oxidizing agent with said substance to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated. t

5. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing an oxidizing agent into said well bore and contacting it with at least a portion of the formation from which the filter cake has been so disrupted and there reacting said oxidizing agent with said substance to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

6. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing an oxidizing agent into said well bore, contacting said oxidizing agent with at least a portion of the formation from which said filter cake has been so disrupted and there reacting said oxidizing agent with said substance to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a result which is a measure of the heat liberated by said reaction whereby the presence of said substance is indicated.

7. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a Well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing an oxidizing agent into said well bore, contacting said oxidizing agent with at least a portion of the formation from which said filter cake has been so disrupted and there reacting said oxidizing agent with said substance at a temperature in the range between 40 C. and 500 C. and at a pressure sufficient to maintain said reaction to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

8. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing perhalogen acid into said well bore and contacting said perhalogen acid with at least a portion of the formation from which the filter cake has been so disrupted and there reacting said acid with said substance to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

9. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing perchloric acid into said well bore, contacting said perchloric acid with at least a portion of the formation from which the filter cake has been so disrupted and there reacting said acid with said substance to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

' 10. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing a solution of perchloric acid having a strength no less than 70% HClO4 into said Well bore and contacting said solution with at least a portion of the formation from which said filter cake has been so disrupted and there reacting said perchloric acid at a temperature in the range between 40 C. and 500 C. with said substance to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

1l. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing an oxidizing agent into said well bore and contacting said oxidizing agent with at least a portion of the formation from which said filter cake has been so disrupted and there reacting said oxidizing agent with said substance in the presence of a catalyst for said oxidizing reaction to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

l2. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing a perhalogen acid into said well bore and contacting it with at least a portion of the formation from which the filter cake has been so disrupted and there reacting said perhalogen acid with said substance in the presence of ceric ammonium nitrate catalyst to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indi- `cated.

13. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing perchloric acid into said well bore and contacting said perchloric acid with at least a portion of the formation from which said filter cake has been so disrupted and there reacting said perchloric acid with said substance in the presence of ceric ammonium nitrate catalyst to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

14. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said Well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing a solution of perchloric acid having a strength in the range between 70% and 84% HClO4 into said well bore, contacting said solution with at least a portion of the formation from which the filter cake has been so disrupted and there reacting said perchloric acid solution with said substance in the presence of ceric ammonium nitrate to liberate heat in that portion of the formation from 'which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

15. A method for detecting the presence of petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises disrupting filter cake from a portion of the face of said formation in the borehole, introducing a solution of perchloric acid having a strength in the range between 70% and 84% HClO4 and ceric ammonium nitrate into said well bore, contacting said solution with at least a portion of the formation from which the filter cake has been so disrupted and there reacting said solution with said substance at a temperature in the range between 40 C. and 500 C. to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation in which heat has been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction,` transmitting said electrical signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

16. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a Well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises displaying a result which is a measure of temperature along a wall of said well bore, disrupting filter cake from a portion of the face of said formation in the borehole, introducing a perhalogen acid reactable with said petroliferous substance into said well bore, contacting said perhalogen acid with at least a portion of the formation from which said filter cake has been so disrupted, reacting said perhalogen acid with said substance to liberate heat in that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation from which heat has been liberated by said reaction to obtain an electric signal which is a function of an increase in temperature in said well bore caused by heat generated by said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

l7. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining on said well bore which comprises displaying a result which is a measure of temperature along a wall of said well bore, disrupting filter cake from a portion of the face of said formation in the borehole, introducing perchloric acid reactable with said petroliferous substance into said well bore, contacting said perchloric acid with at least a portion of the formation from which the filter cake has been so disrupted and there reacting said perchloric acid with said substance at a temperature between 40 C. and 500 C. to liberate heat from that portion of the formation from which the filter cake has been disrupted, contacting said portion of the formation from which heat has been liberated by said reaction with a thermocouple to obtain an electric signal from said reaction which is a function of an increase in temperature in said well bore caused by heat generated by said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal whereby the presence of said substance is indicated.

18. A method for detecting the presence of a petroliferous substance in an earth formation penetrated by a well bore produced by a drilling method which deposits a filter cake lining which comprises disrupting lter cake from a portion of the face of said formation of the borehole, introducing perchloric acid into said well bore, contacting said perchloric acid with at least a portion of the formation from which said filter cake has been so disrupted and there reacting said perchloric acid with said substance to liberate heat in that portion of the formation from which the lter cake has been disrupted, contacting said portion of the formation in which heat has 14 been liberated by said reaction with a thermo-electric means to obtain an electric signal from said reaction, transmitting said electric signal to the surface of the earth and there displaying a function of said signal where- 5 by the presence of said substance is indicated.

References Cited inthe file of this patent UNITED STATES PATENTS 2,270,299 Horvitz Jan. 20, 1942 2,370,793 Horvitz Mar. 6, 1945 FOREIGN PATENTS 373,990 Germany Apr. 18, 1923 573,759 Germany Apr. 5, 1933 

15. A METHOD FOR DETECTING THE PRESENCE OF PETROLIFEROUS SUBSTANCE IN AN EARTH FORMATION PENETRATED BY A WELL BORE PRODUCED BY A DRILLING METHOD WHICH COMPOSITS A FILTER CAKE LINING ON SAID WELL BORE WHICH COMPRISES DISRUPTING FILTER CAKE FROM A PORTION OF THE FACE OF SAID FORMATION IN THE BOREHOLE, INTRODUCING A SOLUTION OF PERCHLORIC ACID HAVING A STRENGTH IN THE RANGE BETWEEN 70% AND 84% HCIO4 AND CERIC AMMONIUM NITRATE INTO SAID WELL BORE, CONTRACTING SAID SOLUTION WITH AT LEAST A PORTION OF THE FORMATION FROM WHICH THE FILTER CAKE HAS BEEN SO DISRUPTED AND THERE REACTING SAID SOLUTION WITH SAID SUBSTANCE AT A TEMPERATURE IN THE RANGE BETWEEN 40 C. AND 500* C. TO LIBERATE HEAT IN THAT PORTION OF THE FORMATION FROM WHICH THE FILTER CAKE HAS BEEN DISRUPTED, CONTRACTING SAID PORTION OF THE FORMULATION IN WHICH HEAT HAS BEEN LIBERATED BY SAID REACTION WITH A THERMO-ELECTRIC MEANS TO OBTAIN AN ELECTRIC SIGNAL FROM SAID REACTION, TRANSMITTING SAID ELECTRICAL SIGNAL TO THE SURFACE OF THE EARTH AND THERE DISPLAYING A FUNCTION OF SAID SIGNAL WHEREBY THE PRESENCE OF SAID SUBSTANCES IS INDICATED. 